Ethylene interpolymer products are widely used in film and molding applications to produce a wide variety of manufactured articles. There is a need to improve the heat deflection temperature (HDT) of ethylene interpolymer products; such products with higher HDT are desired and valued in many applications. Non-limiting examples include: injection molding where a molded part maintains its dimensional stability at higher temperatures, i.e. the molded part has a higher upper use temperature and is functional over a wider temperature range. Further, higher heat deflection temperatures are also desirable in film applications, for example in the packaging of hot foods, or the cooking of foods within a film comprising a least one layer of an ethylene interpolymer product having a higher heat deflection temperature. There is also a need for ethylene interpolymer products having faster crystallization rates in many applications; a non-limiting example includes injection molding where more rapid crystallization allows parts to “set up” or harden more quickly, thus more parts can be produced per hour. There is also a need for ethylene interpolymer products having higher melt strength in many applications. Non-limiting examples include: the production of blown film where higher melt strength improves the stability of the blown film bubble and improved bubble stability allows the production of film at higher rates; higher melt strength is also desired in blow molding and thermoforming applications. Further, higher melt strength is desired in and foam applications where molten ethylene interpolymer products are foamed with chemical or physical blowing agents.
Herein, manufactured articles comprising ethylene interpolymers products having improved heat deflection temperature, faster crystallization rates and higher melt strengths are disclosed.
The ethylene interpolymer products disclosed were produced in a solution polymerization process, where catalyst components, solvent, monomers and hydrogen are fed under pressure to one or more reactors. For ethylene homo polymerization, or ethylene copolymerization, reactor temperatures can range from about 80° C. to about 300° C. while pressures generally range from about 3 MPag to about 45 MPag and the ethylene interpolymer produced is dissolved in a solvent. The residence time of the solvent in the reactor is relatively short, for example, from about 1 second to about 20 minutes. The solution process can be operated under a wide range of process conditions that allow the production of a wide variety of ethylene interpolymers. Post reactor, the polymerization reaction is quenched to prevent further polymerization, by adding a catalyst deactivator, and passivated, by adding an acid scavenger. Once passivated, the polymer solution is forwarded to a polymer recovery operation where the ethylene interpolymer is separated from process solvent, unreacted residual ethylene and unreacted optional α-olefin(s).